How Hurricanes are Named

Today I Found Out has teamed up with Jeremiah Warren to show his awesome “trivia” related videos here, along with Bonus Facts included after the video by me. I hope you enjoy his videos as much as I have.

Hurricanes typically die down very quickly after striking land because they need warm water to continue powering themselves; they are in effect gigantic heat engines. They are powered by so much heat that they can release 50-200 exajoules of heat energy per day. This is about the same amount of energy as would be released by detonating 45,000 nuclear bombs per day of the explosive capacity of “Little Boy”, the bomb dropped on Hiroshima. To put it another way, this is about 200 times more energy than human beings currently have the ability to generate if every electrical power plant on Earth was working at 100% capacity for the entire day. I for one welcome our new hurricane overlords.

The U.S. government once tried to develop a way to stop hurricanes from forming, or at the least weaken them. The attempt was known as “Project Stormfury”, specifically focusing on putting silver iodide in the storms, which would freeze water in the outermost bands of rain, hopefully collapsing the inner eye wall and basically stopping the heat engine in its tracks, or at least reducing its power. While it seemed like it worked a bit at the time, in retrospect, it’s thought that their efforts had almost no effect. One seeded hurricane, Hurricane Debbie, initially reduced its intensity by about 30%, but quickly recovered and was as powerful as ever even after a second seeding attempt. It was later discovered that hurricane eye walls cycle, so that 30% drop was probably just part of the cycle and had little to do with the silver iodide. While they didn’t manage to stop a hurricane, in another attempt, a hurricane that would have struck away from highly populated regions, after being seeded, shifted course and struck Savannah, Georgia. Needless to say, seeding hurricanes with silver iodide isn’t something anyone does any more. Numerous other ideas have been proposed to cool the eye, but the simple fact of the matter is that the amount of heat energy being used here is just too much for any known practical solution to work, even considering the billions of dollars of damage annually hurricanes do.

More to the point, it would be a bad idea to try to stop the hurricanes, even if we could. While tropical storms and hurricanes cause a lot of damage to human settlements, they are actually a critical part of the Earth’s atmospheric circulation system, carrying heat energy from the tropics into colder latitudes, at the same time cooling the upper layers of the ocean over where the storm passes, not just from using the heat energy, but also from churning the water and mixing the upper warm layers with water from the deeper cooler layers of the ocean. They also transport massive amounts of water inland to help relieve drought. Besides the global climate effects, it is thought that if we were to stop this from happening, the waters around the equator would continue to collect heat creating even more massive hurricanes, which would be increasing difficult to stop, possibly even creating a cataclysmic hurricane.

It is theorized by some researchers, such as professor of meteorology at MIT Kerry Emanuel, that such a cataclysmic hurricane may have been what wiped out the dinosaurs. The theory is that an asteroid strike could have heated parts of the ocean as much as 90 degrees Fahrenheit (50 degrees Celsius) over the normal temperatures. The extra heat energy would have resulted in super-hurricanes the likes of which have never been seen by humans, with wind speeds well over 700 mph (1,130 k/h). It wouldn’t just be the wind speeds that would then cause the death of the dinosaurs, but also the fact that this would have allowed water vapor to be carried up into the Earth’s stratosphere, causing catastrophic climate changes.

Even without such a super hurricane, it is thought that lesser “super” hurricanes were the norm even just 1-3 thousand years ago. This is based on core samples taken deep inland near the Gulf of Mexico, which indicate that sand from the ocean was regularly carried far further inland than hurricanes today do and with more regularity (about 3-5 times more hurricanes per year than is the average today).

The word “hurricane” is thought to ultimately come from the Mayan name for the god of storms “Hurukan”.

A tropical cyclone is called a “Tropical Storm” if it has wind speeds within the bounds of 39-73 mph (34-63 knots). Above that (74 mph and up) and it is called a hurricane. Anything above 111 mph or 96 knots is known as a “Major Hurricane”. When a storm begins showing wind speeds of 38 mph it is called a “tropical depression”.

Hurricanes are classified differently depending on what country you live in. In the United States, typically the Saffir-Simpson Hurricane Wind Scale is what’s used, classifying the hurricanes from Category 1 through Category 5, based on their sustained wind speeds. This scale was developed by a structural engineer, Herbert Saffir, and a meteorologist, Bob Simpson, in 1971. Saffir developed the scale trying to estimate the amount of property damage a specific hurricane would do, primarily looking at the damage the wind would do to structures. Simpson then tweaked it based on flood damage. What they came up with were the following dividing lines:

Category 1: 74-95 mph

Category 2: 96-110 mph

Category 3: 111-129 mph

Category 4: 130-156 mph

Category 5: 157 mph and up

Despite the somewhat less intimidating sound of the name “tropical storm”, these can cause major damage and result in many deaths, often due to flooding. For instance, Tropical Storm Allison had wind speeds of just 60 mph at its peak, but managed to do over $5 billion worth of damage and kill 41 people after dropping over 40 inches of rain in a span of just 15 days, destroying just under 3000 homes and damaging another 70,000.

Hurricanes can drop as much as 2.4 trillion gallons of rain per day.

In the last 3 decades, on average there were about 6 hurricanes per year from the Atlantic Ocean, with an additional 5 tropical storms. Only about 3 hurricanes every 2 years will actually strike the U.S. coast and typically only 1 of those three will be considered a major hurricane. All total in the world there are about 100 tropical cyclones per year.

Even if hurricanes don’t hit anywhere near land, they can still cause human deaths from people swimming on the coast. For instance, Hurricane Bertha some 1,000 miles off the coast managed to kill 3 people in New Jersey via creating a rip tide. An additional 1,500 people had to be saved by rescue teams in Maryland from the same effect thanks to Bertha.

The hurricane season in the Atlantic, Caribbean, and Central Pacific is between June 1st and November 30th. In the East Pacific, it lasts from May 15 to November 30. Finally, in the Western North Pacific, there is no season, it can happen any time.

If hurricanes and tropical storms with their sustained wind, flooding, and lightning strikes weren’t bad enough, they also often produce tornadoes which can touch down at any time within the hurricane. These are usually fairly short lived and so you won’t typically be given much warning as to when one will develop near you if you’re in a hurricane.

The eye of a hurricane typically is about 20-30 miles wide (32-48 km), though ones as large as 230 mi (270 km) have been recorded. While the eye of the hurricane tends to be fairly calm (except at sea where the water can be anything but calm in the eye), the “eye wall” surrounding the eye is where the heaviest rains and winds usually can be found in the hurricane, thus where much of the wind damage happens as it hits land. The eye will also be the warmest spot in the hurricane, known as the “warm core”. At the center of these giant heat engines, you’ll also find some of the lowest atmospheric pressures that can be found anywhere at sea level on Earth.

Approximately 90% of all deaths as a result of a hurricane result from the “storm surge”, which is a rise in the water level that surges onto land, contributing to flooding with the massive amount of rain often dumped by these storms. Storm surges can reach as high as 20 ft (6 m) and can be as long as 100 miles and extend into the coast as much as 25 miles (40 km) in a typical hurricane.